a(n) = n! * Sum_{k=0..floor(n/4)} (n/4)^k /(k! * (n-4*k)!).

A362314

a(n) = n! * Sum_{k=0..floor(n/4)} (n/4)^k /(k! * (n-4*k)!).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =25a(5) =151a(6) =541a(7) =1471a(8) =84001a(9) =925345a(10) =5682601a(11) =25177681a(12) =2245355641a(13) =35901100951a(14) =312222474565

External references